Expanding mandrel



' Oct.- 6, 1931. c. J. SHENK EXPANDING MANDREL Filed March 29, 1929 2 Sheets-Sheet l Oct. 6, 1931. c. J. SHE NK EXPANDING MANDREL Filed March 29. 1929 2 Sheets-Sheet 2 IN VEN TOR.

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Patented Oct. 6, 1931 ETED STATES CHARLES .T. SHENK, OF WESTMINSTER, PENNSYLVANIA EXPANDING MANDREL Application filed March 29, 1929. SerialNb. 351,073.

In the operation of lathes it is not uncommon to place the material having a bore on a mandrel. The commonest form of these mandrels is a solid mandrel of very slight taper on which the material is forced sufliciently to secure it. Another form has been used, commonly called an expanding mandrel which has adjusting blades which may be adjusted to different diameters. This whole structure is ordinarily adjusted before its insertion into the work and the work is driven, or forced onto the mandrel in the usual manner.

The present invention is directed to improving adjustable or expansion mandrels and is so formed that the expansion and tightening in the work is accomplished by the mere setting up of the mandrel in the lathe centers. Features and detailsof the invention will appear from the specification and claims.

Preferred embodiments of the invention are illustrated in the accompanying drawings as follows 6 Fig. 1 shows a central section of the mandrel with the expanding blades in collapsed position.

Fig. 2 a similar view with the blades expanded.

Fig. 3 a section on the line 3-3 in Fig. 1.

Fig. 4- a section on the line H in Fig. 2.

Fig. 5 a section on the line 5-5 in Fig. 6 showing an alternative construction Fig. 6 a section on the line 66 in Fig. 5.

Fig. 7 an end view of one of the body portions.

Fig. 8 a section on the line 88 in Fig. 7.

1 marks the expanding blade carrier. This has a. central opening 2 extending through it. Radially extending slots 3 extend through the walls of the carrier and into the central opening. Expanding blades 4 are arranged in the slots 3. The carrier has telescoping end pieces 5 and 7 the end piece 5 having a centering socket 6 and the end piece 7 a cen: tering socket 8. The centering socket 8 is preferably carried in an end piece provided with roller bearings 9.

The inner ends of the end pieces 5 and 7 are tapered at 10 and these ends engage small bevels 11 on the inner corners of the expandingplates. i i

In operation the mandrel'is placed in the work, placed in the lathe and the tail piece set up. As the tail piece exerts pressure endwise on the carrier theplates are exparid ed through the tapered end pieces 5 and 7 engaging the inner walls of the work.- If there is a slight taper in the bore ofthe work the blades automatically center and-take up 6o this variation. The rollerpbearing' assures the proper rotative support at the tail piece even under considerable pressure.

In order to lock the blades against accidental removal from the slots I preferto provide the blades with n otches 12 at their ends and arrange'retaining rings 13 on the body of the carrier- These rings may be slit over the notched portion of the blades.

In order to prevent accidental removal of to the end pieces 5 and 7 these end pieces have notches 14 arranged therein and retaining pins 15 extend throughthe walls of the body intothese notches. The notches are elongat ed so that the end pieces mayhave the necessary longitudinal movement to expand the blades for the proper operation of the mandrel.

In the alternative construction shown in Figs. 5 to 8 the carrier is formed of the end pieces 16. These end pieces have lathe centers 1-7 and 18, the lathe center 18 beingcarried by a plug with a roller bearing 19. A central expanding pin 20-has tapered surfaces 21 at each end and extensions 22 at each end, the extensions 22 projecting into openings 23 in the body end 16.

Expanding plates 24 are arranged in slots 25 extending radially in the carrier pieces 16. The lower ends of these blades are beveled at 26 to correspond to the tapers of the surfaces 21. The faces of the plates are provided with shoulders at 27 and a retaining plate 28 is secured'on the'end of the carrier pieces 16 by set screws 2811. Work 29 is shown in place. 1 The operation of this device is quite similar to that of the structure shown in Figs. 1 to 4. The carrier as a whole is contraetible and through the contraction of the carrier the expandin plates are ex anded to engage the work. T e carrier is p aced in a lathe as in the preceding structure with the work in place thereon, the tail screw set up, thus contracting the carrier and with the contraction the ta red ends 21 operating on the expanding bfides expand them into engagement with the work,

What I claim as new is 1. In an expanding mandrel, the combination of radially mnvahle work supporting plates having work engaging surfaces on their ripheral edges; and an axially contracti le carrier for the plates having radially extending guides in which the plates are sliclably mounted and comprising tapered surfaces engaging the plates said carrier having centering ends and actuating the plates through the contraction of the carrier in response to pressure on the centering ends.

2. In an ex. nding mandrel, the combination of radi 1y movable work so porting plates ha'ving work engaging sur aces on their peripheral edges; an axially contractible carrier for the plates having radially extending guides in which the plates are slidably mounted and comprising tapered surfaces engaging the plates said carrier having centering ends and actuating the plates through the contraction of the carrier In response to pressure on. the centering ends; and means for retaining the plates in the carrier.

3. In an expanding mandrel, the combination of radially movable work supporting plates having work engaging surfaces on their peripheral edges; an axially contractible carrier comprisnig a body having a central opening and radial slots receiving the plates, and. centering and supporting pins in tin o ning having tapered ends engaging the tea and actuating them with an inwar movement of the pins in response to pressure on the 4. In an expanding mandrel, the combination of radially movable Work supporting plates having work engaging surfaces on their peripheral edges; an axially contractihle carrier comprisin a body having a central opening and r ial slots receiving the a; centering and supporting pins in the opening having tapered ends engaging the plates and actuating them with an inward movement of the pins in response to pressure on. the pins; and means retaining the plates in the slots.

5. In an expanding mandrel, the combinatiun of'radially movable work supporting plains having work engaging surfaces on their peripheral edges; an axially contractible. carrier comprising a body having a central. opening and radial slots receiving the plates; centering and supporting pins in the 0 lug having tapered ends engaging the garland actuating them with an inward my hand.

CHARLES J. SHENK.

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